Cam grinder



y 1941- H. E. BALSIGER ETAL 2,243,410

CAM GRINDER Filed July 22, 1938 e Sheets-Sheet 1 lNVENTORS HmeoLp cams/E2 May 27, 1941.

H. E. BALSIGER ETAL CAM GRINDER Filed July 22, 1958 6 Sheets-Sheet 2iNVENTORS HA RdLD 5.541.5/45)? BY RALPH E. PRICE TORNEY \v ZZZ/Z vm v a71% QESQQQ$ May 27, 1941.

6 Sheefs-Sheet s lnnentord HA RoLD .BALS/GER, RALPH '5. PRICE GttomegMay 27, 1941- H. E. BALSIGER ETAL 2,243,410

CAM GRINDER Filed July' 22, 1938 6 Sheets-Sheet 4 INVENTORS HAROLDEBALSIGER BY RALPH E PR! 5 4/ A TORNEY y 1941- H. E. BALSIGER ETIAL2,243,410

CAM GRINDER Filed July 22, 1938 6 Sheets-Sheet 5 Imnentor HAROLDE-BALSIG'ER RALPH 5. PRICE Gttorneg May 27, 1941.

H. E. BALSIGER ETAL CAM GRINDER 6 Sheets-Sheet 6 Filed July 22, 1938311ventor HAROLD E-BALSIGER RALPH E.PRICE Gttomeg Patented May 27, 1941CAM GRINDER Harold E. Balsiger and Ralph E. Price, Waynesboro, Pa.,assignors to Landis Tool Company,

Waynesboro, Pa.

Application July 22, 1938, Serial No. 220,777

27 Claims.

Our invention relates to grinding machines, particularly machines forgrinding automotive cam shafts, and it is an object to provide a machinein which the various functions are performed automatically in a rigidsequence, that is, each successive function is controlled or initiatedby one or more preceding-functions.

A further object is to provide a standard timing mechanism forcontrolling the cycle of operations of the machine.

A further object is to provide means operable by movement of the cradleto inoperative position to stop the timing mechanism and permit same tobe re-set for the next operation.

A further object is to provide means for automatically dressing thegrinding wheel at each end of the carriage movement.

In the drawings:

Figure 1 is a front elevation of a cam grinding machine.

Figure 2 is a right hand end view of the headstock in section along line2-2 of Figure 1.

Figure 3 is an end elevation of the wheel reciprocating mechanism.

Figure 4 is a combined wiring and piping diagram.

Figure 5 is a plan view of the headstock with the top cut away.

Figure 6 is a front elevation of the wheel spindie reciprocatingmechanism.

In the drawings, Figure 1, numeral indicates the bed of a cam grindingmachine having a work carriage II slidably mounted thereon; a cam shaftI3 is rotatably supported on said work carriage between the headstock I2and the tailstock I4. A motor 49 is mounted on said headstock and drivessame thru a suitable arrangement of belts and gears. Numeral indicates awheel base slidably mounted on bed I0 for movement toward and from camshaft 13. Grinding wheel I6 is rotatably mounted on bearings on saidwheel base. Motor I8 for driving grinding wheel 16 is mounted on thewheel base 15. A hand wheel II together with suitable gearing (notshown) provides means for adjusting the wheel base toward and from thework. The structure and cycle of operation of our invention resembles ina general way that of the machine disclosed in Steiner Patent 2,017,927granted October 22, 1935. The dressing device I9 having a handwheel 80for adjusting same is shown in detail in Greiner et al. application119,704 filed January 8, 1937.

In Figure 2 is shown a right hand elevation of the headstock in section.A work cradle 84 pivotally mounted on said carriage at rotatablysupports a master cam 86 in axial alignment with work piece cam shaftI3. Said master cam is urged into engagement with a,rol1er 81 on shaft88 by a spring 43, acting thru arm 89 to rock said cradle and themembers carried thereby in a clockwise direction. Said roller is mountedfor axial movement on shaft 88 in timed relation with the movement ofcarriage II by a mechanism disclosed in detail in Ott Patent 1,993,854granted March 12, 1935. Said spring is mounted in a cylindrical member90 and is supported on disks 9I and on a rod 92. One end of said rod isinserted in a cylindrical guide member 93 in the end of cylinder 90; theother end has a rounded head which abuts against the surface of a notchin arm 89. An adjustable stop member 94 on said rod determines the limitof movement of said rod to the left in Figure 2.

Piston rod 96 of piston 42 abuts against the opposite side of arm 89 andwhen under influence of pressure at the head end, causes said arm tomove in a counter-clockwise direction to separate said master cam andsaid roller. Another cam 91 is mounted to rotate with said master cam.Mounted in headstock I2 opposite said cam is a normally closed switch48. In the position shown said cam does not touch said switch. However,when piston 42 rotates arm 89 and cradle 84 in a counter-clockwisedirection, the nose of said cam rotates thru the position shown indotand dash lines and opens said switch. The fluid entering the head endof cylinder 4| is directed thereto by a valve I62 and passesunrestricted thru a check valve I40. Exhaust fluid from said head end ofsaid cylinder must pass thru a throttle valve MI. The same line whichconducts fluid to the head end of cylinder 4| also directs fiuid to anormally closed pressure switch 221. Said pressure switch is held openby either pump pressure or exhaust pressure. After the fluid isexhausted from said head end of said cylinder the switch is permitted toclose. The function of this switch is to start and stop the timing cycleas will be described later.

Wheel spindle reciprocating mechanism The wheel spindle reciprocatingmechanism is the same as that shown in OttPatent 1,844,791 grantedFebruary 9, 1932, except that it is ac- 'tuated hydraulically instead ofmanually as in engages a worm wheel I05. Said worm wheel rotates freelyon shaft I06. Attached to said worm wheel is one-half of a clutchelement I81. The other half I08 forms one end of a spool I88, the otherend having a toothed portion II8 engaging a plate III having similarteeth and secured to wheel support 15. Said spool is slidably keyed toshaft I66. At one end of said shaft is an adjustable eccentric II2positively connected thru a bracket II3 to spindle IOI so that rotationof said eccentric effects an axial reciprocation of said spindle. A'yokeIl4 fits between the ends of said spool and is attached to a piston rod5 of piston H6 by means of a connecting member I I4. Said piston isslidably mounted in a. cylinder II1. Fluid under pressure is directedinto said cylinder by a valve 210 to move said piston in one directionand a spring II8 moves it in the opposite direction.

Feed mechanism The mechanism for feeding the grinding wheel toward thework is shown in Figure 4 and is similar to that shown in Patent2,150,749 granted March 14, 1939. Said mechanism consists of a rapidfeed or positioning piston I20 in a cylinder I 2| and a piston I22 incylinder I23. Movement of said pistons to an inoperative position islimited by an adjustable stop I24. Said pistons are connected to wheelsupport 15 thru a feed screw which is integral with said pistons, and anut (not shown). Integral with said pistons and located between them isa pinion I25. Said pinion engages a rack I26 having a power piston I21at one end in cylinder I28, and a dash pot piston I28 in cylinder I30 atthe other end. An adjustable stop I3I limits the movement of piston I21toward inoperative position. Said piston I21 acting thru said rack andsaid pinion rotates a feed screw (not shown) which provides a controlledfeed movement of grinding wheel 16 toward work piece 13. The supply offluid under pressure to the rapid feed cylinder I2I is directed to oneside or the other of said cylinder by a reversing valve I80 thru linesI88 and I88. Said valve is shifted in one direction by a solenoid 240,and in the opposite diretion by a spring I8I. An extended portion I82 ofvalve I 80 serves as a dash pot piston. A portion of the reversing valvebody is bored to provide a cylinder for said piston. Additional boresprovide the necessary passages in which are inserted a check valve I83and a throttle valve I84. This dash pot functions only when valve I80 isshifted in a direction to cause a separation of the wheel 16 and work13. The purpose is to retard the movement of the valve and therebyprevent too abrupt a withdrawal of the grinding wheel.

Fluid under pressure is supplied to cylinder I28 from a valve I62 thrueither of lines 232 or 235. A dash pot mechanism for controlling themovement of piston I21 consists of the dash pot piston I28 and acylinder I30 described above. Operating fluid for said dash pot iscontained in a reservoir I32. Said reservoir and said cylinder areconnected by a passage in which is mounted a throttle valve I33. Abypass passage around said throttle valve is controlled by a valve I34.The bypass valve I34 is shifted to bypass position by a. spring I35.Said valve is shifted in the opposite direction by fluid under pressurefrom line 233. Said line is a branch of line 232 thru which fluid underpressure is directed to the head end of cylinder I28 to start thegrinding feed movement.

Work carriage traverse mechanism 6 Movement of the work carriage H iseffected by a motor consisting of a cylinder I68 and a piston I68slidably mounted therein. A piston rod I18 is secured to said carriagein any suitable manner (not shown). Fluid under pressure is directed toone end or the other of said cylinder by a reversing valve I65 thrulines I16 and I11. Said valve may be positioned by means of a lever I66the movement of which" is guided by a T shaped opening in a guide plate2. Passage I18 havingga connection to each end of cylinder I66 has acomparatively small opening, and serves to bleed air out of the cylinderwhile preventing escape of any appreciable volume of fluid underpressure. The traverse speed is controlled by throttle valve 226 inexhaust line 238 providing valve 223 is closed so as to preventunrestricted passage of exhaust fluid therethru from reversing valveI65. Line I16 leading to the head end of cylinder I68 has two shortbranch lines, one of which leads thru a throttle valve I" to thereservoir, the other of which leads to a cylinder I13. A piston I12 isslidably mounted in said cylinder and a spring I14 urges said piston tothe right. An adjustable stop I15 limits the movement of said pistontoward the left. The function of valve I is to compensate for the area.of piston rod I10 during the slow down period just before the plungerI64 enters one of the notches 82 in spacing bar 8| on carriage 1I. Saidvalve I1I is effective only on exhaust pressure, i. e., when thecarriage H is moving from right to left. The function of piston I12 isto compensate for the area of the piston rod I10 during the exhaust offluid thru line I16 so as to delay the release of plunger I64 afterwithdrawal thereof from one of the notches 82. If it was not for thiscompensation, the plunger would be released more quickly during themovement of the carriage from right to left than from left to right,because of the difference in volume of the exhaust fluid from the twosides, and might return to the notch from which it had just beenwithdrawn. Valve I56 is shifted in one direction by pressure, to directfluid to withdraw plunger I 64. As soon as the carriage piston I69begins to move, exhaust fluid passes thru reversing valve I65 and actsagainst the lower end of displacement'piston I58. Said piston rises andpicks up valve I56 shifting same to a position to connect passage 300with an exhaust line and thus permit plunger I64 to be returned tocontact with spacing bar 8I by the action of spring 306. The rate atwhich displacement piston I58 is shifted depends upon the volume of theexhaust fluid. This volume is greater from the head end of the cylinderI68 than from the rod end. The difference in volume is used in shiftingpiston I12 thus leaving the volume for actuating piston I58 the same forboth ends of cylinder I68. This equality of volume exists only while thecarriage travels far enough to prevent plunger I64 from returning to thesame notch from which it has just been withdrawn.

Index mechanism The means for effecting intermittent movement ofcarriage H to place aseries of cams in position to be ground consists ofa standard timing mechanism having a motor I85. Said for rough andflnish grinding.

motor thru a clutch controlled by a solenoid 2:8 drives a series ofaxially aligned relay operating cams for actuating contacts I88, I81 andI88.

Contact I88 controls the traverse speed by closing a valve 223 whichprevents a free escape of exhaust fluid and causes said fluid to beexhausted at. a much slower rate thru throttle valve 228. The rate oftraverse movement may be controlled also thru a switch 22I as will bedescribed later. The traverse speed may be varied by adjusting valve225. Said contact also controls the timer motor I85. Contact I81energizes alternately the coils of relays 220 and 23I to control thespeed of headstock motor 49 7 Contact I88 controls the movement of thegrinding wheel away from the work thru solenoid 240 and valve I80.

A spacing bar 8| adjustably mounted on carriage 1i has formed therein asuccession of notches each of which corresponds to a cam on a cam shaftto be ground. Said notches do not extend the full width of the bar. Thepurpose of this construction is to prevent breaking the portion betweennotches, particularly where said notches are close together. Thestructure is further strengthened by making the bottom of the notchcurved so as to eliminate corners. Said spacing bar may be adjustedlongitudinally by means of adjusting screws held in blocks 88 on saidcarriage and abutting the ends of said bar. The means for locating thespacing bar BI and carriage 1! includes a plunger I64 in the to of whichis formed a slight projection I64. The purpose of this projection is topermit plunger 84 to first enter the notch to the extent of saidprojection. This movement is just enough. to cause arm 245. to actuateswitch 22I to close a circuit across the lower contacts thereof thusenergizing solenoid 222 to shift valve 223 to a position to prevent thepassage of exhaust fluid therethru. In this position said valve 223prevents the flow of exhaust fluid from the traverse motor thru valve225 and causes it to flow thru valve 228 which has a smaller capacityand therefore reduces the traverse speed. Said plunger is an elongatedvalve stem on a valve I82. A lever 45 pivoted at M5 hasan arm extendinghorizontally therefrom to'engage said plunger. Another arm 245 extendsin the opposite direction from said first mentioned arm to a position toactuate a two pole switch 22I and a limit switch 241. At each end ofspacing bar BI is a stop member 2 38 inserted therein and protrudingbeyond the lower edge of said bar. Said stop serves to engage theplunger E88 and determines the limit of movement of the carriage in eachdirection. A pair of cam members 55 are mounted on said carriage andspaced so as to actuate a switch 20! during the period when the carriagemoves from the last notch to the stop 288. The function of said switchis to control the work drive motor 48 and the dressing mechanism ineither direction.

Control valve mechanism Fluid under pressure is supplied to the grindingfeed mechanism, the traverse mechanism, and the cradle withdrawalmechanism from pump I5 2 thru a valve I82. An extended portion of saidvalve forms the plunger I88 which engages the notches 82 in spacing barSI for locating the work carriage ll in successive grinding positions.Pressure to operate said plunger and valve is supplied from a pump I54thru passages I55 and I8I to valve I58 and then thru another passage 300to the top of valve I82. Said fluid also is directed .sage 3! to valveI5I.

withdraw plunger I84 from notch 82, the piston I88 begins to movecarriage 1|. The plunger must be held retracted until after thismovement has started otherwise it will return to the same notch. Part ofthe exhaust fluid passing thru valve I85 is directed against piston I58and shifts same into valve I58. The valve does not move until saidpiston has completed its travel therein. When said valve is shifted itconnects the top of valve I82 with an exhaust passage 305 and spring 308returns said valve I82 and plunger I84 until said plunger engagesspacing bar 8| in readinessto drop into the next notch. The delay inshifting valve I58 permits suflicient movement of carriage II to preventthe return of plunger I84 to the notch from which it was flrstwithdrawn. When the exhaust is from the head end of cylinder I88 anadditional delay device is provided in the piston I12 in cylinder I13described in connection with the traverse mechanism. Valve I58 is firstactuated by fluid under pressure directed thereto from valve I5I thrupassage I51. However, when valve I5I returns to its initial positionthis passage is open to exhaust. Valve I58 is then held by fluid whichis directed from itself thru passage 300. Valve I 5I is shifted in onedirection by a piston I52 in cylinder I53. When fluid'under pressure isdirected by valve 880 thru line I89 to cylinder I23 to cause a reversemovement of the grinding wheel support, it also passes on thru passage Ito cylinder I53 to shift piston I52 and valve I5I to the right'against aspring. In this position of valve I5I, fluid from supply passage I55 isdirected thru passage I51 to actuate valve I58 as described above. ValveI82 receives fluid under pressure from passage I8I and after beingdepressed said valve distributes said fluid thru pas- Valve I5I in itsleft hand position directs this fluid thru a passage 302 to valve I85which in turn directs it thru passages I18 or I11 to one side or theother of piston I88 in cylinder I88. Valve I85 may be shifted manuallyby lever l88 thru arm I81. Fluid from the same port in valve I82 isdirected thru passage 235 and valve I40 in passage 238 to the head endof cylinder 0! to act on piston 82 therein and rock the work cradle 08to place the work in an inoperative position. Said fluid passes 'on thrupassage 23'l to actuate pressure switch 221. Passage 235 leads to therod end of slow feed cylinder E28. When valve I82 is in the position inwhich plunger I68 rests in one of the notches 82 in spacing bar iii, thehead end of cylinder I28 is supplied from said valve thru passage 232.

Dressing devices The details of the dressing device are described Ifully in Greiner et al. application 119,704 filed January 8, 1937.However, the principal elements of said device will be describedbriefly.

The dressing device 19 is mounted for adjust ment toward and from wheel18 by means of a hand wheel 80 and associated elements. A

ratchet (not shown) on said hand wheel is actuated alternately by pawlson pistons 258 and 258.

The length of travel of these pistons, and hence the magnitude of thefeed impulse, is adjustable by means of screws 266 and 261. In this casethe first feed impulse, that effected by piston 258, is greater thanthat effected by piston 259. The

reason for this is to give a better surface to the grinding wheel. Thedressing device 13 is mounted on a slide (not shown) and traversedacross the grinding wheel by means of a piston 28L A dog 264 movablewith said slide actuates a switch 268 to reverse the dressing traverse.The wheel feed hand wheel 11 is actuated during thedressing operation bymeans of atpawl in a piston 260. The travel of said piston may beadjusted by screw 213. The traverse speed of the dresser is controlledby throttling the exhaust from each end of cylinder 350. Throttle valve263 is set to permit a comparatively rapid movement of the diamond inits roughing cut from right to left. Fluid is supplied to the head endduring this stroke thru check valve 262 which permits a free flow.During traverse in the opposite direction the exhaust from the head endcannot pass thru the check valve. Throttle valve 268 is set to permit acomparatively slow movement for a finishing cut of the diamond on thewheel.

Operation Current is supplied to the entire machine when switch I90 isclosed. With the carriage H in one of the end positions, cam 55depresses the plunger 200 of switch I to complete a circuit from supplyline 3 thru line 202 to said switch MI, and then thru the coil of relay203 to energize same and return thru the: normally closed contact ofrelay 204 to line I. With relay 203 energized the circuit to relay 205is complete except for push button switch 206. Closing said switchpermits current to flow from line 3 thru switch 206, relay 203, line201, the coil of relay 205 and return to line I. Contact 208 of relay205 provides the holding circuit for said relay. Closing said relaystarts the wheel drive motor 18 and the motor for pump I54 (not shown).Contact 208 of relay 205 completes a circuit to the coil of relay 209except for push button switch 2I0. Said switch may be closed by theoperator to complete a circuit thru relay 209 to the dressing mechanism.Once this switch is closed the holding circuit keeps the relay closed solong as the main switch I90 remains in closed position. The dressingoperation will then be initiated by switch 20I, as will be describedlater.

The main control lever I66 moves in a T shaped guide plate 2. Movementto left or right shifts valve I65 to direct fluid under pressure to oneside or the other of traverse cylinder I 68. Movement of said lever atright angles to said first movement actuates a two position switch 2I2.In the normally closed position of switch 2I2, as shown in Figure 4, thecontrol relay C2 for work drive motor 49 is energized thru line -3I0,and the normally closed contact of C3, to the relay C2, and then to lineI, and thru line 3 and the normally closed contacts of switch 20I, line202 to line 3. Line 3I0 is common to both sides of switch 2I2. The otherside of said normally open contact is connected thru line 3I2, contact208 of relay 205, and the stop side of switch 206 to line 3. I

As carriage 1| begins to move away from the end position, cam 55 permitsswitch 20I to return to normal position in which a circuit from line 3passes thru line 202 to said switch, and then thru the normally closedside of switch 2I2 and line 3Il| to the control panel oi motor 48. Saidmotor is arranged to travel at either a fast or slow speed, dependingupon the condition of the timing relay I81-and the timer clutch relays228 and 238. While the timing mechanism is inoperative all the relaysoperated thereby are in position for starting a cycle. This conditionexists when the carriage'moves from its end position, and the circuitfrom line 3 thru switch 208, contact 208 to relays I81 and 230 and line3I5, is such that the coil of motor control relay 220 is energized andthe motor started at a slow speed. The purpose of the slow speed at thistime is to lessen the impact between the master cam and roller followeras the cradle 84 advances the workto grinding position. As the traverseproceeds, the tip I64 on plunger I64 drops into the flrst of the notches82 in spacing bar 8I. Lever 45 swings in a counter-clockwise directionto close the lower contacts of switch 22I. Closing said contactscompletes a circuit from line 3 thru switch 20I, line 3I6, timing motorI85, contact I88, and line I, to energize solenoid 222 and shift valve223 against spring 224. Said valve closes on the less restricted exhaustof fluid from traverse cylinder I68 thru speed control valve 225,leaving as the only outlet, the valve 226 which is adjusted to permitonly a small volume of fluid to pass thru and thus reduce the speed ofthe carriage just before the rest of the plunger enters the notch.Switch'22l is operable thru the same circuit to start timing motor I85,although the clutch which starts the actual timing cycle is not closeduntil later. When plunger I64 enters notch 82, valve I62 is shifted by aspring .to its upper position and releases fluid from cradle cylinder 4Ithru throttle valve I4I, thru line 236, valve I62, and exhaust line 248.Spring 43 thru arm 89 moves the cradle and work to operative position ata rate determined by the setting of valve I. The action of said springis supplemented by fluid under pressure from valve I62, thru lines 232and 234 to the rod end of cylinder 4|. The exhaust pressure of thisfluid is sufllcient to hold pressure switch 221 in open position. Whenthe discharge of fluid from the cylinder is completed, that is when themaster cam engages its follower, said pressure switchwill be closed tocomplete a circuit from" line 3 to line 25I and switch 252 to energizethe clutch operating solenoid 228 of the timer, and thus start the.timing cycle. The contact arrangement of the timing relay is such thatwhen the clutch magnet is energized, the normally open and normallyclosed contacts of relay230 reverse. their positions. The normallyclosed contact opens and deenergizes the coil of slow speed relay 220and the normally open contact closes and energizes the coil of highspeed relay 23I. Said coil also actuates relays 229 and 238. The circuitthru the normally closed contact of relay 230 to the coil-of slow speedmotor relay 220 is broken and a circuit is completed from line 3 thruthe normally; open contact of relay I81, the normally open butnow closedcontact of relay 230 and the normally closed contact of time relay I81to the coil of the fast speed motor relay 23I. At the same time, thecircuit to slow speed relay 220 of motor 49 is broken by the opening ofthe normally closed circuit thru relay 230.

When plunger I64 drops in one of the notches 82, valve I62 connectspressure supply line "I thru chamber A of said valve with a line 232leading to the head end of cylinder I28, thus starting the grindingfeed. A branch line 233 directs fluid under pressure to shift valve I34so as to stop the unobstructed passage of fluid from cylinder I36 toreservoir I32 and to cause said fluid to pass at a controlled rate thruneedle valve I33. The rate of the grinding feed may be varied by use ofvalve I33.

The upward movement of valve I62 stops the flow of fluid under pressurefrom chamber B thereof, thru valve II to the traverse cylinder I68, andalso to valve I56. Thus, when the plunger I64 enters a notch, valve I62is positioned to direct fluid under pressure to advance the work cradle84, to start the grinding feed, and to cut off the supply of fluid underpressure to the traverse motor.

As described above, the timing relay clutch is energized by closing ofpressure switch 221 after the cradle has advanced to grinding positionwith the work rotating at slow speed.

At the end of the rough grinding operation the relative positions ofrelays I81 and 236 are again reversed, this time due to the action ofthe timing mechanism on relay I81. Current then passes thru the normallyopen contacts of relay I81, and thru line 3I5 to the coil of slow speedmotor relay 226. At the same time the coil to high speed relay 23I isdeenergized by the opening of the circuit thru the normally closedcontact of relay I81 and line 3I1. Thus the work is caused to rotate atslow speed for finish grinding.

At the end of the finish grinding period timing contact I88 is opened todeenergize thru line 3I6 the feed'valve solenoid 246 and permit valveI86 to be shifted to reverse position by spring I8I. This movement ofthe valve is controlled by a dash pot piston I82 on one end of saidvalve so that while fluid under pressure is directed thru line I89 tocylinder I23 to act on piston I22 to back off the grinding wheel asquickly as possible, the controlled valve movement prevents the wheelfrom being started with a jerk which would be likely to leave anobjectionable mark on the work. The movement of the wheel support isvery slight, not more than g inch, since the purpose of the movement ismerely to effect a break of contact between wheel and work. Thismovement is limitedby adjustable stop I24. Valve I86 also supplies fluidunder pressure thru lines I89 and I95 to cylinder I53 where it acts onpiston I52 to shift valve I5I against a spring. This movement of valveI5I directs fluid from supply line I55 thru line I51 to the top of valveI56. This supply of fluid under pressure first resets the displacementpiston I59 inside valve I56 against adjustable stop I66 and then shiftsthe valve I56 to admit fluid thru passage 366 to the top of valve I62 towithdraw plunger I64 from the spacing bar BI. Fluid from the samepassage is directed to the upper disk of valve I56 and serves as ahydraulic holding circuit after valve I5I returns to its originalposition. Upon withdrawal of plunger I64, arm 245 on lever 45 opens thelower contacts of switch 22I and closes the top contacts. Opening thelower contacts of said switch opens a circuit from line 3 thru line 3I6and deenergizes the timer mot-or I85 and also solenoid 222. The circuitthru said top contacts energizes solenoid 222 thru switch 241 and line3I6 and holds valve 223 in position to; block the exhaust thru line I11and valve I65 from cylinder I68 so as to provide sufficient pressure toshift valve I56. Valve I56 then relieves the pressure on valve I62 byconnecting passage 366 with exhaust passage 365 to permit plunger I64 tomove against spacing bar 8|. With this movement of the plunger, switch22I moves to neutral position, solenoid 5 222 is therefore deenergized,spring 224 shifts valve 223 to position to permit exhaust fluid fromtraverse cylinder I68 to escape thru passage 3I9, valve 225, valve 223,and exhaust passage 212 and the traverse movement proceeds at highspeed.

Shifting valve I62 also reverses the cradle operating piston 42 bydirecting fluid under pressure from chamber B of said valve thrupassages 235 and 236, and check valve I46 to the head end of cylinder4|, and opening the other end thru passages 232 and 234 and chamber A ofsaid valve to exhaust line 246. This causes the cradle and work to bemoved away from grinding position to permit indexing to the next cam.Fluid under pressure from said chamber B of valve I62 is also conductedthru passage 235 to the rod end of cylinder I28 to reset the grindingfeed, and at the same time valve I34 is reset by spring I35 which forcesfluid back thru passages 233, 232, and chamber A of valve I62 to exhaustpassage 246 to permit a free flow of fluid back to cylinder I36 fromreservoir I32.

The fluid under pressure which withdraws the cradle also opens pressureswitch 221 thus deenergizing timer clutch solenoid 228 to disengage theclutch and permit the timer to be reset.. At the same time relays 229and 236 return to normal position in which position, as previouslydescribed, the slow speed relay 226 of motor 49 remains energized.Resetting the timer permits closing of relay I88 which energizessolenoid 246 to shift valve I86 to direct fluid under pressure thrupassage I69 to the head end of cylinder I 2I, where it acts on pistonI26 to return the wheel support 15 and grinding wheel 16 to grindingposition. Thus, the wheel is returned to working position before theindex movement takes place, and-is ready to start grinding as soon asthe cradle brings the next cam into position. When valve I86 is shiftedby solenoid 246, fluid is exhausted therethru from cylinder I53 thrupassages I 95 and I89 to exhaust passage 212, and valve I5I is returnedtoits original position by its spring. The passage 36I from valve I62 tovalve I65 is opened thru valve I5I and passage 362 to one side or theother of traverse cylinder I 68 depending upon the position of valveI65. Fluid is exhausted from the top of valve I56 thru \passage I51,valve I5I, and exhaust passage 365, but as described above, the samefluid which 55 withdraws the plunger I64 acts on the upper disk of saidvalve I56 to hold same in the downward position.

As soon as the traverse movement begins, assuming that it is from rightto left, the exhaust 60 fluid from cylinder I 68 after passing thrupassage I16 to valve I acts first to shift the displacement piston I59in valve I56 to the limit of its movement inside said valve. The exhaustfluid then shifts displacement piston I12. After this, valve I56 isshifted against the holding pressure which is permitted to escape thrucheck valve 326, chamber B of valve I62, and passage 235, which at thistime is open to exhaust thru valve I65, and the pressure on the top ofvalve I62 is connected thru valve I56 with an exhaust line 365. Theplunger I 64 is thus released against the spacing bar. If the traversemovement should be from left to right, valve I56 would be moved as soonas the displacement piston I59 7 therein had reached its limit ofmovement because displacement piston I12 is not effective under linepressure, the supply of fluid under these conditions not being limitedto the volume of the cylinder and connecting parts.

Piston I12 is provided to compensate for the area of the piston rod "6,and any compensation aflorded thereby is eifective only insofar as theshifting of displacement piston I56 is concerned. For this reason valveIII is also needed when traversing from right to left to make thetraverse slow down equal in both directions of traverse. This slow downis caused by shifting valve 226 to block the exhaust of fluid thruthrottle valve 225 and passage 3|! and causing said fluid to dischargethru the smaller opening of valve 226. The speed of the slowmovement,'of course, is determined by the setting of valve 226.

When plunger I64 is released against the spacing bar, the traversemovement continues at full speed until the tip I64 enters the nextnotch. This slight movement of the plunger is effective thru arm 245 toclose the lower contacts of switch 22I. Said contacts complete a circuitfrom lines 3, 3I6 and I to energize solenoid 222 which shifts valve 223to perform the function described above. Said switch alsostarts timingmotor I65. Shortly thereafter the plunger enters the notch completely,and valve I62 connects the head end of cylinder H with the exhaust line246 thru throttle valve HI and passage 236 to permit the cradle toreturn to working position. This movement is controlled by valve I4I.Fluid under pressure from line I55 is also directed by valve I62 in thisposition thru passage 262 to the head end of cylinder I28 to start thegrinding feed. As soon as the cradle 84 has been returned to operativeposition, the reduction in exhaust pressure at the head end of cylinder4I permits the closing of pressure switch 221 completing a circuit fromline 3, thru line 25I, and snap switch 252, to energize timer clutchsolenoid 226 and start a new cycle.

When it is desired to control the traverse movement manually, theoperator may depress lever 45 to withdraw plunger I64 from the spacingbar, and at the same time thru arm 245 close the upper contacts ofswitch 22 I. Said lever may be held in depressed position by a latch(not shown). Withdrawal of the plunger, and consequent shifting of valveI62, will have the same effect as though operated automatically, exceptthat to cause the rapid traverse, lever 45 must be depressed far enoughso that arm 245 will open limit switch 241 and thus neutralize theaction of switch 22I. When the slow down is desired the operatorreleases the lever enough to permit switch 241 to close again, but notenough to open the upper contacts of switch 22I.

After the last cam has been ground, withdrawal of plunger I64 permits aslight traverse movement which brings a stop 246 on spacing bar 6| intocontact with plunger I64 to stop said traverse movement. At the sametime cam 55 opens the normally closed circuit and closes the normallyopen circuit of switch 26I. Rotation of motor 46 is maintained thrutappet switch 246 until cam 91 opens same. Said cam is effective to opensaid switch only when the cradle 64 is in back position. Opening saidswitch breaks a circuit from line 3 thru a normally open contact 325 ofrelay C2, thru line 3, normally closed contact of switch 2I2, and line3), the normally closed contact of relay C3 to deenergize relay C2, thusopening the circuit to motor 43. However, relay 02 has a normally closedcontact 621 which closes a ciruit from line I to the coil of reverserelay C3; and from there thru line 626 and zero speed switch 250 to line3. A reverse current is sent thru motor 43, and just at the reversalpoint said zero speed switch 256, which has been held closed by forwardrotation of the motor, opens the reverse circuit to stop said motor andthe headstock spindle in a predetermined position.

Closin the normally open contacts of switch 26I directs current thruline 25I to energize solenoid 226 of the timing mechanism to close relaycontact 223. This connects line 3 with line 6I6 thru switch 22I, thetiming motor I65, and thru contact I66 of the timer to line I. At thesame time solenoid 222 is energized and valve 226 shifted to preventpassage of exhaust fluid therethru, thus to eifect the traverse slowdown so as to cushion the movement of stop 246 against plunger I64. Atthe end of the predetermined period the timer will open relay I66,breaking the circuit from line 6 to line 3", and stopping the motor I65,and shifting valve 223 to again release exhaust fluid from cylinder I66to permit the next movement of the carriage to occur at a rapid rate.The timing mechanism may be disconnected thru a two pole snap switch252. The other pole of said snap switch is connected to the dressingmechanism.

Closing the normally open contacts of switch 26I is efiective to connectlines 3 and 326 thru relay 266 and lines 636, 33I and relay 264 to lineI to energize solenoid 255 and shift valve 256 so that fluid underpressure from line 251 is directed thru passage 340 to the diamond feedpistons 256 and 259 to feed one and reset the other; thru passage 64I towheel feed piston 266 to feed the wheel a distance equal to the wear,plus the amount to be removed by dressing; and thru passage 642 andcheck valve 262 to the head end of the dresser traverse piston 26I. Thedresser makes the first pass across the wheel at a speed determined bythe setting of valve 263 which controls the exhaust of fluid from therod end of piston 26I. At the end of the flrst pass a dog 264 movablewith piston 26I releases normally closed switch 265 which completes acircuit from line 3 thru snap switch 252 to energize and hold energizedthe coil of relay 264. Opening the normally closed contacts of saidrelay breaks the circuit from line I thru-line 33I to solenoid 255deenergizing same and permitting valve 256 to be shifted by spring 345to its initial position. Fliud under pressure will then be directed thrupassages 3 and 344 to the opposite end of each of the pistons 256 and259 to cause the flrst to reset and the second to effect a feed movementsmaller than that of 256. The amount of feed in each case may beadjusted by means of stop screws 266 and 261. The shorter feed movementis accomplished by adjusting the screw 261 to shorten the stroke ofpiston 253. Fluid under pressure is directed thru passage 3 and valve263 to the rod end of traverse-piston 26I. The speed of said piston onthe reverse movement is less than on the first pass and is determined bythe setting of valve 266 which controls the flow of exhaust fluid onsaid reverse movement. Movement of piston 26I to the right is limited bystop screw 266. Fluid is also directed at this time thru passage 3 tothe right hand end of piston 266 to reset same. Movement of said pistonto the right is limited by stop screw 213.

At the beginning of the dressing operation when solenoid 255 isenergized, fluid under pres sure from valve 256 is directed thru passage342 to one end of a pressure operated valve 210. Said valve in turnconnects cylinder Hl with exhaust line 212. Piston H6 is shifted byspring 8 to separate clutch members I01 and M8 to stop reciprocation ofthe wheel spindle NH and grind-v ing wheel 16 during the dressingoperation. Said reciprocation remains stopped until the next grindingoperation is started. When valve I62 directs fluid to the head end ofcylinder I28 to start the grinding feed it is also directed thru line21! to the opposite endof valve 210. This connects cylinder H! withpressure line 251 and piston H6 is shifted against spring H8 to engagethe clutch members and start the reciprocating movement again.

We claim:

1. In a grinding machine, a work support, a wheel support, means forrotating a work piece on said work support, means for effecting arelative transverse movement between said supports, means responsive tosaid transverse movement for changing the speed of said work rotatingmeans at the beginning of a grinding operation, and a control mechanismoperable before the end of the grinding operation for changing said workspeed back to the initial rate.

2. In a. grinding machine. a wheel support. a work support, means onsaid work support for rotatably supporting a work piece, means forrotating said work piece, means for effecting a relative transversemovement between said supports, means for effecting an intermittivelongitudinal movement of said work support for successively placing aseries of portions on said work piece in position to be ground includinga timing mechanism, means actuated by said timing mechanism for changingthe speed of work rotation, means actuated also by said timing mechanismfor initiating said transverse movement for separating said work supportand said wheel support, means for stopping said timing mechanism withthe work rotating at slow speed, means for returning said work supportand wheel support to grinding position, means responsive to saidmovement for starting said timing mechanism again and means actuated bysaid timing mechanism for increasing the work speed.

3. In a grinding machine, a work support, a wheel support, means foreffecting a relative transverse movement between said supports,

mechanisms for effecting said movements intermittently to grindsuccessive portions of a work piece, means for rotating the work at apredetermined speed, means for automatically reducing said speed duringthe grinding operation on each of said portions, means for initiatingsaid transverse movement for separating the work and wheel and meansresponsive to said transverse movement in returning said wheel and workto operative position for restoring said predetermined speed to saidwork rotating mechanism.

4. In a grinding machine, a feed mechanism comprising a piston. acylinder, a supply of fluid under pressure for effecting a relativemovement between said parts, a dash pot for controlling said movement, athrottle valve in said dash pot, a valve normally positioned forbypassing fluid around said throttle valve and means for directing saidfluid under pressure simultaneously to actuate said valve to cut offsaid bypass and to said cylinder to initiate a feeding movement.

5. In a grinding machine, a work support, a wheel support, means foreffecting relative transverse and longitudinal movements between saidsupports including a hydraulic motor for each movement, a valve forcontrolling each of said motors, means for actuating each of said valvesin a predetermined sequence including a timing mechanism, a switchactuated by said timing mechanism for shifting the valve for causingsaid transverse movement, a second valve actuated by first valve in onedirection to direct fluid for shifting a third valve, a plunger forlocating said work support in'predetermined positions during saidlongitudinal movement, means responsive to fluid under pressure fromsaid third valve for withdrawing said plunger, a valve operable withsaid plunger for directing fluid under pressure to said second valve,means whereby resetting said timer releases said second valve and meanswhereby release of said timer operated valve is effective to directfluid to one side or the other of said work support motor.

6. In a grinding machine, a wheel support, a work support, means forfeeding said Wheel support toward and away from said work supportincluding a motor, a reversing valve for controlling same, power meansindependent of cross feed movement for actuating said reversing valve inone direction after a predetermined grinding operation, and a dash potfor cushioning the movement of said valve whereby to prevent an abruptstart in moving said support.

'7. In a grinding machine, a movable carriage, a hydraulic motor forcausing a traversing movement of said carriage, said motor including acylinder, a piston slidably mounted therein, a piston rod extending thruone end of said cylinder, fluid supply lines to each end of saidcylinder, means for effecting said traversing movement intermittently tolocate successive portions of a work piece in position for grindingincluding a spacing bar and plunger, a valve for effecting withdrawal ofsaid plunger which prevents release thereof before the beginning of saidtraverse movement, means for equalizing the action of said valveregardless of the direction of movement including means for compensatingfor the difference in effective area of the two sides of said pistonincluding an escape valve in the line leading to the head end of thecylinder whereby to permit sufficient fluid to escape during exhausttherethru to compensate during cushioning for the displacement of thepiston rod.

8. In a grinding machine, a movable carriage and hydraulic means formoving same including a piston and cylinder, a piston rod on saidpiston, pipe lines leading to opposite ends of said cylin-v der fordirecting fluid under pressure alternately thereto, means for effectingsaid carriage movement intermittently in either direction to locate aseries of portions on a work piece in position for grinding including aspacing bar and plunger for engaging spaced portions thereon, means forslowing down the movement of the carriage just before said plungerengages one of said portions, means for equalizing the length of saidslow movement in each direction including means to compensate for thedifference of effective area between the two ends of said pistonincluding a spring pressed piston, a cylinder connected to the fluidline leading to the head end of said cylinder, said compensating meanshaving a displacement equal to the difference in displacement betweenopposite sides of said carriage piston as said piston moves thru thesame distance in each direction.

9. In a machine of the kind described, a work support, means forenecting a longitudinal movement of said work support including a motor,means for causing intermittent operation of said motor including a.timing mechanism, means for reducing the speed of said motor as saidsupport approaches the end of its movement in one direction and meansactuated by said timing mechanism ior rendering said speed reducingmeans inoperative before said support begins to move in the ppositedirection.

10. In a machine of the kind described, a work support, a grinding wheelsupport, a grinding wheel mounted thereon, means for effecting an axialreciprocating movement of said wheel, a wheel dressing device on saidwheel support, mechanisms for eflecting relative transverse andlongitudinal movement between said supports including a motor, means foreflfecting said movement intermittently to position said grinding wheeland successive portions of said work piece in operative relation, meansfor shifting said work support to an inoperative: position after apredetermined number of grinding operations, means responsive to saidlast movement to initiate operation of said dressing device and to stopsaid reciprocatingmovement including a switch, a valve actuated by saidswitch for directing fluid under pressure for initiating said dressingoperation, a second valve actuated by fluid under pressure from saidfirst mentioned valve for controlling operation of said wheelreciprocating mechanism.

11. In a machine of the kind described, a work support, a wheel support,a grinding wheel rotatably mounted thereon, mechanisms for effectingrelative transverse and longitudinal movement of said supports, meansfor effecting said longitudinal movement intermittently to place thetool support and the work support in successive positions to grind aseries of portions on a work piece including a motor, a spacing barhaving notches spaced to correspond with the spacing of the portions ofsaid work piece to be ground, a plunger and resilient means for holding.same in contact with said spacing bar, meansv for withdrawing saidplunger and starting said motor and means operable in response tomovement of said motor for releasing said plunger.

12. A machine of the kind described having a work support, means foreffecting an intermittent longitudinal movement of said work supportincluding a hydraulic motor having inlet and exhaust lines attachedthereto, said exhaust line having two branches, avalve in one of saidbranches for permitting the discharge of a comparatively small volume offluid, a valve in the other branch of said exhaust line which isadjustable for controlling the speed of the motor, a second valve" inthe same branch with said adjustable valve, means including a time delaymechanism and a solenoid actuated thereby for shutting off said secondvalve whereby to leave only said first mentioned valve for releasing theexhaust fluid and thus substantially reduce the speed of said motor.

13. A cam grinder having a work support, means for efiecting anintermittent longitudinal movement of said work support including ahydraulic motor having inlet and exhaust lines attached thereto, endstops for determining the limit of said longitudinal movement in eachdirection, an exhaust line having two branches, a

valve in one of said branches for: permitting the discharge of acomparatively small volume of fluid, a valve in the other branchof saidexhaust line which is adjustable for controlling the speed of the motor,a second valve in the same branch with said adjustable valve, and aswitch actuated by movement of said work support Just before an endstopis reached for shutting oi! said second valve whereby to leave only saidfirst mentioned valve for releasing the exhaust fluid and thinsubstantially reducing the speed of said motor.

14. A cam grinding machine having a work support, a wheel support, meansfor enacting relative longitudinal movement between said supportsincluding a motor, means for eifecting said movement intermittentlyincluding a specing bar, a plunger for successively selected portions ofsaid bar. and a switch operable by movement of said plunger just priorto engaging one of said portions for controlling said motor to reducethe speed thereof and thus reduce the rate of said longitudinal movementjust before stopping said movement completely.

15. In a grinding machine, a grinding wheel support, a work support,mechanism including a main control valve for effecting relativetransverse and longitudinal movement between said supports, mechanismindependent of said work sup rt for dressing said grinding wheelincluding a valve, mechanism for eii'ecting a reciprocating movement ofsaid grinding wheel, a pressure operated valve for controlling saidreciprocating mechanism, said pressure operated valve being shifted inone direction by fluid under pressure from said dresser control valveand in the opposite direction main control valve.

16. In a machine of the kind described, a work support, a grinding wheelsupport, a grinding wheel mounted thereon, means for effecting an axialreciprocating movement of said wheel, a wheel dressing device on saidwheel support, mechanisms for effecting relative transverse andlongitudinal movement between said supports including a motor, means foreiiecting said movement intermittently to position said grinding wheeland successive portions of said work piece in operative relation, meansfor shifting said work support to an inoperative position after apredetermined number of grinding operations, means responsive to saidlast movement to initiate operation of said dressing device and to stopsaid reciprocating movement'including a switch, a valve actuated by saidswitch for directing fluid under pressure for initiating said dressingoperation, a second valve shifted in one direction by fluid underpressure from said first mentioned valve for stopping said wheelreciprocating mechanism.

17. In a machine of the kind described, a work support, a grinding wheelsupport, a grinding wheel mounted thereon, means for eiiecting an axialreciprocating movement of said wheel, a wheel dressing device on saidwheel support, mechanisms for effecting relative transverse andlongitudinal movement between said supports including a motor, means forefifecting said movement intermittently to position said grinding .wheeland successive portions of said work piece in operative relation, meansfor shifting said work support to an inoperative position after apredetermined number of grinding operations, means responsive to saidlast movement to initiate operation of said dressing device and to stopsaid reciprocating movement including a switch, a valve actuated by saidswitch for directing fluid under pressure for initiating said dressingoperation, a second valve shifted in one by 'fiuid under pressure fromsaid 7 direction by fluid under pressure from said first mentioned valvefor stopping said wheel reciprocating mechanism, and a main valve forcontrolling said relative transverse and longitudinal movements which iseffective also after one of said portions has been positioned to directfluid under pressure to shift said second valve in the oppositedirection for starting said reciprocating movement. r

18. In a grinding machine, a work support, a cradle oscillatably mountedon said support, mechanism for rotating a work piece including a motor,a pair of switches in parallel for controlling rotation of said motor,one of said switches being operable by movement of said work support, acam rotatable with the work for actuating said second switch forstopping said work in a predetermined angular position, said camoperated switch being operable only when said cradle is in apredetermined position.

19. In a grinding machine, a work support, a-

grinding wheel support, mechanism for effecting relative transverse andlongitudinal movements of said supp rts including a motor for each,means operable when a work piece has been ground to size for initiatingsaid transverse movement to separate said wheel and work including avalve which is shifted for a short period and then returned to itsoriginal position whereby to effect a quick withdrawal and rapid returnof said transverse movement, a valve shifted by the same fluid underpressure which actuates said rapid feed, for directing another supply offluid under pressure to actuate a pilot valve which controls withdrawalof the plunger and directs fluid under pressure to actuate said traversemechanism.

20. A grinding machine having a work support and a grinding wheelsupport, mechanisms for efiecting intermittent relative transverse andlongitudinal movements of said supports for successively positioning aseries of portions to be ground on a work piece including a spacing barand a plunger for engaging selected portions thereon, size controlmechanism and means operable thereby for initiating said transversemovement including a valve for directing fluid under pressure to saidtransverse moving mechanism, and means actuated by fluid under pressurefrom said valve for withdrawing said plunger from said spacing bar andinitiating said longitudinal movement, including a valve actuated bymovement of said plunger.

21. In a cam grinding machine, a wheel support, a grinding wheel'mountedthereon, a work support, a cradle rockably mounted on said work supportfor movement toward and away from said wheel, mechanisms for efiectingrelative transverse and longitudinal movements between said supports,means for efiecting said movement intermittently to place a series ofportions of a work piece in position to be ground including a spacingbar and plunger, a timing device for determining the duration of thegrinding on each of said portions, a valve actuated by said timingdevice for withdrawing said wheel support, a second valve actuated byfluid under pressure from said first mentioned valve, a valve actuatedby fluid under pressure from said second valve for directing fluid towithdraw said plunger, a valve movable with said plunger for directingfluid to move said cradle to inoperative position, a pressure switchactuated by said cradle operating fluid for stopping and resetting saidtiming mechanism, means responsive to resetting said timing mechanismfor returning said first two valves to original position, and meansoperable upon return of said second valve to original position forinitiating said longitudinal movement.

22. In a cam grinding machine, a bed, a wheel support slidably mountedthereon, a grinding wheel rotatably mounted on said support. means foreffecting a transverse movement of said support including a valve, awork support, means for eifecting a longitudinal movement of said worksupport, a work cradle oscillatably mounted on said work support formovement toward and from said wheel support, a valve for controllingsaid work support and said cradle, means for effecting movement of saidwork supports, wheel support and cradle at intervals to positionselected portions of a work piece for grinding including a spacing barand plunger for locating said parts and a timing device for determiningthe duration of the grinding operation, a valve for eflecting withdrawalof said plunger from said spacing bar, a main control valve forcontrolling said work support and cradle valve and said plunger controlvalve, means actuated by said timing device to shift said wheel supportcontrol valve to break contact between the wheel and work, and also todirect fluid under pressure to shift said main valve, said plungercontrol valve being operable in response to said main valve when soshifted to direct fluid for withdrawing said plunger, said work supportand cradle valve being shifted simultaneously with withdrawal of saidplunger, means operable in response to fluid under pressure foroperating said cradle for stopping said timing mechanism-means operableupon stopping said timing mechanism for returning said wheel supportcontrol valve to original position whereby to return said wheel supportto grinding position and said main valve to its original position, saidmain valve upon return to said original position being effective todirect fluid under pressure from said work support control valve to movesaid work support.

23. In a grinding machine, a work support, a wheel support, mechanismsfor effecting relative transverse and longitudinal movements betweensaid supports, means for efiecting first a transverse movement of thewheel support thru a distance just suflicient to break contact betweenthe work and wheel, means for effecting a transverse movement of the'worksupport for vcausing a further separation of work and wheel, andmeans operable in timed relation with said transverse movement of thework support for returning the grinding wheel to operative positionsubstantially immediately after said transverse movement of the worksupport.

24. In a grinding machine, a work support, mechanism for efiecting alongitudinal movement thereof, mechanism for eiiecting said movementintermittently for grinding successive portions on a work piece and thenshifting said work support to an inoperative position, a cradleoscillatably mounted on said support for moving said work transverselyto inoperative position during said longitudinal movement, mechanism forrotating a work piece including a motor, a pair of switches in parallelfor controlling rotation of said motor, one of said switches beingoperable switch for stopping said work in a predetermined angularposition but only at the end of said longitudinal movement in eitherdirection.

25. In a grinding machine, a wheel support, a work support, a cradleoscillatably mounted on said support, fluid pressure mechanism formoving said cradle toward and from operative position, a grinding wheelsupport, mechanism for efiecting intermittent relative transverse andiongitudinal movement between said supports including a timing mechanismmounted independent of other mechanisms on the machine, and a pressureswitch operable in response to the fluid under pressure for actuatingsaid cradle for starting and stopping said timing mechanism.

26. In a grinding machine, a work support, a grinding wheel support, agrinding wheel rotatably mounted thereon, mechanisms for eflectingintermittent relative transverse and longitudinal movements of saidsupports for successively grinding a series of portions of a work-piece,a dressing tool mounted independently of said work support, mechanismfor eflfecting a relative traversing movement between said dressingdevice and said grinding wheel, a reversing mechanism for controllingoperation of said dressing device, a switch for automatically shiftingsaid reversing mechanism in one direction at the end of saidlongitudinal movement whereby to initiate the dressing operation, andmeans responsive to said dresser traverse movement for shifting saidreversing echanism in the opposite direction whereby I cause saiddressing tool to again pass across the grinding wheel and return tostarting position.

27. In a grinding machine, a grinding wheel support, a grinding wheelrotatably mounted thereon, a work support, mechanisms for eflectingintermittent relative transverse and longitudinal movements of saidsupports for successively grinding a series of portions of a work piece,mechanism including a reversing control for effecting said longitudinalmovement in both directions, a dressing tool mounted independently ofsaid work support, mechanism for eflecting relative movement betweensaid dressing device and said grinding wheel, a control device forinitiating operation of said dressing mechanism, a member operable inresponse to said longitudinal movement in one direction for actuatingsaid control device at a predetermined point in said movement, andanother member operable in response to said longitudinal movement in theopposite direction for actuating said control device at anotherpredetermined point in said longitudinal movement.

HAROLD E. BAISIGER. RALPH E. PRICE.

